As is known, today's rotary-drum home laundry dryers comprise: a substantially parallelepiped-shaped outer boxlike casing structured for resting on the floor; a substantially cylindrical, bell-shaped revolving drum structured for housing the laundry to be dried, and which is housed in an axially rotating manner inside the casing to rotate about its horizontally-oriented longitudinal axis, directly facing a laundry loading/unloading opening formed in the front wall of the casing; a door hinged to the front wall of the casing to rotate to and from a closing position in which the door rests completely against the front wall of the casing to close the laundry loading/unloading opening and airtight seal the revolving drum; and an electric motor assembly structured for driving into rotation the revolving drum about its longitudinal axis inside the casing.
Home laundry dryers of the above type are also provided with an open-circuit or closed-circuit, hot-air generator which is structured to circulate inside the revolving drum a stream of hot air having a low moisture content, and which flows through the revolving drum and over the laundry inside the drum to rapidly dry the laundry; and with an electronic central control unit which controls both the electric motor assembly and the hot-air generator to perform one of the user-selectable drying cycles stored in the same central control unit.
With reference to U.S. Pat. No. 3,789,514 and U.S. Pat. No. 3,816,942, to reduce production costs of the rotary-drum home laundry dryers, in the last years the bell-shaped revolving drum has been replaced by a sleeve-shaped revolving drum which consists of a substantially cylindrical, rigid tubular body structured for resting horizontally inside the appliance casing aligned to the laundry loading/unloading opening, on a number of horizontally-oriented supporting rollers which are located near the two axial ends of the tubular body, and are fixed to the appliance casing in free revolving manner so to allow the tubular body to freely rotate about its horizontally-oriented longitudinal axis.
The front rim of the tubular body is coupled in an airtight and axially rotating manner to the periphery of a funnel-shaped element which extends from the front wall of the appliance casing, towards the tubular body, and is shaped so as to converge to the laundry loading/unloading opening; whereas the rear rim of the tubular body is coupled in an airtight and axially rotating manner directly to the rear wall of the appliance casing.
More specifically, to avoid air leakages from the two axial ends of the tubular body, a first annular sealing gasket is interposed between the front rim of the tubular body and the periphery of the funnel-shaped element on the front wall of the casing, whereas a second annular sealing gasket is interposed between the rear rim of the tubular body and the rear wall of the appliance casing.
In currently marketed rotary-drum home laundry dryers, the first annular sealing gasket is recessed into a circular groove deep-drawn on the periphery of the funnel-shaped element, whereas the second annular sealing gasket is recessed into a circular groove deep-drawn on the rear wall of the appliance casing. Both annular sealing gaskets are firmly glued to the appliance casing, usually on the bottom of the groove, so as to remain stationary when revolving drum rotates about its longitudinal axis, and the front and rear rims of the tubular body scrape in airtight manner against the corresponding annular gasket.
Despite allowing a considerable reduction of the appliance production costs, the removal of the rear wall of the revolving drum has caused a slight reduction of the working life of the laundry dryer.
Long-term working life of this type of rotary-drum home laundry dryer, in fact, is usually conditioned by the lifetime of the two annular sealing gaskets, i.e. by the thickness of the two annular sealing gaskets, and thickness of the annular sealing gasket fixed to the rear wall of the appliance casing is heavily limited by the relatively small depth of the circular groove realizable on the rear wall of the appliance casing.
In today's rotary-drum home laundry dryers, in fact, the relatively small thickness of rear wall of the appliance casing does not allow deep-drawing of very deep circular grooves.
In addition to the above, positioning and gluing of the annular sealing gasket on the bottom of the circular groove realized on the rear wall of the appliance casing is relatively complicated and takes a lot of time during assembly of the laundry dryer, thus partly defeating the production costs savings resulting from the removal of the rear wall of the bell-shaped revolving drum.